Folding bicycle

ABSTRACT

A folding bicycle includes a frame ( 10 ) with a main member ( 11 ) extending in the fore and aft direction of the bicycle and a rear wheel assembly ( 19 ) in the region of a rearward end of the member ( 11 ). The assembly ( 19 ) is pivotably connected with the frame to be movable between a use position in which a rear wheel ( 20 ) of the assembly in side elevation of the bicycle is disposed rearwardly of the frame and a folded position in which the wheel in the side elevation is disposed partly alongside the main member ( 10 ). A pivot connection allowing lateral redisposition of the wheel in this manner can have the form of a hinge ( 31 ) with a horizontal axis inclined relative to the vertical longitudinal plane of the bicycle.

The present invention relates to a folding bicycle.

Folding bicycles are in widespread use in urban and other environmentsin circumstances where folding into more compact dimensions is ofadvantage to assist storage in buildings or for convenience in otherforms of transport, such as rail carriages and motor vehicles. To besuccessful, such a bicycle has to not only be capable of folding into asmall size for convenient carrying and storage, but also has to have astiff and lightweight structure so that it rides in much the same way asa normal bicycle.

The positions of the three points of contact with the rider, i.e.saddle, pedals and handlebars, cannot be significantly altered from astandard bicycle without an adverse effect on ride, efficiency of useand rider comfort. Thus, the number and disposition of fold points iscritical to a satisfactory design. For example, the greater the numberof fold points the smaller the achievable fold package, but the less therigidity in the unfolded, use state and the greater the overall weight.In addition, many existing designs require the use of non-standard basiccomponents, such as wheel hubs and gearing systems, which increaseproduction costs and prevent later mixing and matching of parts.

It is therefore the principal object of the present invention to providea folding bicycle which can be folded at the rearward end in a compactmanner, but retains a lightweight and stiff structure at this end in theunfolded or use state.

A subsidiary object of the invention is to provide a folding bicyclewith a rear construction which, notwithstanding inclusion of a foldingsystem, permits utilisation of selected standard components, for examplerear wheel and hub and a chain drive system.

According to the present invention there is provided a folding bicycleincluding a frame with a main member extending substantially in the foreand aft direction of the bicycle and a rear wheel assembly disposed inthe region of a rearward end of the member, the assembly being pivotablyconnected with the frame to be movable between a use position in which arear wheel of the assembly in side elevation of the bicycle is disposedrearwardly of the frame and a folded position in which the wheel in theside elevation is disposed partly alongside the main member.

In the case of such a bicycle rearward end arrangement, folding of therear wheel is achieved without the need for a fold location within theassembly as such or within the frame, the fold point being located at ajunction of the assembly and the frame so that the structural integrityof each of the two principal components of assembly and frame need notbe diminished. Due to the provided overlap of the rear wheel and themain fore and aft member of the frame, the rear part of the bicycle hascomparatively small dimensions in the folded state of the rear assemblyso that a compact package for transport, including carrying by the user,and storage can be achieved.

Preferably, the assembly is pivotably connected with the frame to bepivotable about an axis disposed at such an inclination relative to avertical longitudinal plane of the bicycle that in the use position therear wheel is disposed substantially in the longitudinal plane and inthe folded position in a plane inclined relative to the longitudinalplane. By provision of, in effect, an angled pivot joint at the point ofpivotal interconnection of the frame and assembly the assembly duringmovement into its folded position can swing progressively out of thebicycle vertical longitudinal plane, in relation to which in the useposition it will normally be symmetrically disposed, so that the rearwheel is able to move alongside the main frame member rather than merelybelow that member as in most conventional folding systems. In the foldedposition the rear wheel will thus lie generally in a plane at a smallangle relative to the bicycle vertical longitudinal plane.

The inclination of the axis of pivotation of the rear wheel assemblyrelative to the bicycle vertical longitudinal plane is preferablysubstantially 5°, which should be sufficient for the rear wheel to beable to lie alongside the frame by the time the wheel has travelled fromthe use position of the assembly to a point at which the frame isencountered. A greater or lesser angle of inclination may be appropriatedepending on, in particular, the width dimensions of the variouscomponents of the assembly. The angular range of travel of the assemblybetween the use position and the folded position may also depend onspecific constructional aspects, but is typically in the vicinity of180°.

The assembly is preferably pivotably connected with the frame in arearward base region thereof, for example at a seat tube of the frame.Such a location of the point of pivotal interconnection of the frame andassembly creates a precondition for swinging the assembly downwardly andthen upwardly alongside the frame. In addition, the assembly ispreferably detachably connected with the frame at a spacing from thepivotable connection, so that the assembly, in the use position, has twospaced-apart points of attachment to the frame. The provision of twosuch points at a spacing from one another makes a significantcontribution to the structural rigidity of the unit of frame and rearwheel assembly in the use position of the latter, thus the state inwhich the bicycle is ridden. The detachable connection can be by way ofquick-action fastening and unfastening means, so that the assembly canbe quickly released for pivoting and equally quickly secured in placefor use of the bicycle.

As a further particularly advantageous feature the bicycle can includechain drive means for driving the rear wheel and a chain collectingdevice to collect a chain of the chain drive so as to take up slack inthe chain on movement of the assembly from the use position to thefolded position. Pivotation of the rear wheel assembly into the foldedposition produces slack in the chain which could cause the chain todetach from, for example, sprockets of the drive means. For this reason,provision of a chain collecting device of the kind mentioned ensuresthat the chain remains in place throughout the folding and unfoldingprocesses.

For preference, the chain collecting device comprises deflecting meansto engage an upper and a lower run of the chain during movement of theassembly from the use position to the folded position and toprogressively deflect the runs by formation in the upper run of a benddirected away from the lower run and by formation in the lower run of abend directed towards the upper run. Such deflecting means is preferablyengageable with the underside of each run and can be arranged to causethe deflected runs to cross over one another during movement of theassembly from the use position to the folded position. Collection of thechain by formation of bends in the runs and causing the runs to crossover one another maintains tension in the chain in a simple manner sothat the chain does not depart from its associated sprockets or otherdriving and driven elements. The deflecting means preferably comprisescurved guide surfaces, for example circumferential surfaces ofcylindrical elements, for deflection of the runs therearound. Thesecylindrical elements can be mounted on a bracket attached to the frameat the base thereof, the bracket and elements in that position beingable to be located partly within the perimeter of a drive sprocket ofthe drive means so that there is minimal increase in the size of thebicycle in its folded state.

The bicycle may further comprise a steering assembly disposed in theregion of a forward end of the frame and carrying a front wheel movablebetween a use position in which the wheel in side elevation is disposedforwardly of the frame and a folded position in which the wheel in theside elevation is disposed partly alongside the main member at the otherside of the frame from the rear wheel in the folded position of the rearwheel assembly. The bicycle in folded state then represents aparticularly compact package, especially if the two wheels are disposedin substantially parallel planes in the folded positions of theassemblies.

Compactness of the bicycle in its folded state is further enhanced ifthe frame comprises a seat tube receiving a seat post which protrudesfrom an upper end thereof and carries a seat, the seat post beingretractible and extensible relative to the seat tube. The seat post,which will carry the riders seat, can thus be retracted into the seattube so that the seat may be located in the vicinity of the frame.Moreover, the seat tube can be open at a lower end thereof to permit theseat post to extend out of the tube at its lower end when retracted,whereby the lower part of the retracted seat post can jut out of theseat tube in an area which is, in any case, partly occupied by othercomponents, such as the rear wheel drive systems. The seat post ispreferably securable in a fixed relationship to the tube by quick-actionsecuring means, so that release of the post and subsequent fixing in ause position can be carried out easily and quickly.

An embodiment of the present invention will now be more particularlydescribed by way of example with reference to the accompanying drawings,in which:

FIG. 1 is schematic side elevation of a bicycle embodying the invention,showing a rear wheel assembly of the bicycle in use position;

FIG. 2 is a view similar to FIG. 1, but depicting only the rear part ofthe bicycle and showing the rear wheel assembly part way between the useposition and a folded position; and

FIG. 3 is a view similar to FIG. 2, but showing the rear wheel assemblyin the folded position.

Referring now to the drawings there is shown a folding bicyclecomprising a frame 10 having as basic elements a relatively deep mainframe member 11 extending in the fore-and-aft direction of the bicycle,a down tube 12 extending downwardly from the main member at a locationslightly behind the midpoint of its length and a seat tube 13 secured toand extending downwardly between the rearward end of the main member andthe lowermost end of the down tube. The main member 11, which can be afabricated hollow aluminium body, carries at its forward end a head tube14 in which a steering assembly 15, inclusive of handlebars 16 and afront wheel 17, is rotatably mounted. The front wheel 17 is carried bywheel carrier 18 which is foldable so that the unit of carrier and wheelcan lie against the frame 10 to reduce the size of the bicycle in thefront region. Folding is achieved by way of a hinge connection of thecarrier 18 to front forks of the steering assembly in the region of theperimeter of the front wheel 17 and a detachable connection of thecarrier to the forks in the region of the wheel axis by way of aquick-release clamping mechanism. Specific details of the constructionand folding capability of the front wheel carrier are not relevant tothe present invention and accordingly are not discussed.

At the rearward end of the bicycle a foldable rear wheel assembly 19 ispivotably connected with the frame 10 to be movable between a useposition in which the bicycle can be ridden and a folded position inwhich the rear part of the bicycle is reduced to compact dimensions tofacilitate transport and storage. The assembly 19 comprises a rear wheel20 and a rear wheel carrier composed of a lower—or chain—stay 21 and anupper stay 22 rigidly connected with the lower stay, the stays extendingdivergently from a meeting point at a hub of the wheel 20 and supportingthe wheel by way of an axle associated with the hub. Each stay is, infact, formed by a respective arm on each side or the wheel; the arms ofeach stay can remain separate over their length or unite outwardly ofthe circumference of the rear wheel.

The rear wheel carrier is pivotably connected to the frame 10 by way ofa hinge 23 coupling the lower stay 21 to the seat tube 13 at its lowerend and detachably connected to the frame by way of a quick-actionfastening and unfastening device 24 coupling the upper stay 22 to theseat tube 13 at its upper end, thus at a spacing from the hinge 23. Theaxis of the hinge 23 is disposed to be substantially horizontal and atan inclination of approximately 5° to the vertical longitudinal plane ofthe bicycle, the rear wheel assembly 10 being generally disposed in thisplane in its use position. After operation of the device 24 to uncouplethe upper stay 22 from the seat tube 13, the rear wheel assembly 19 canbe pivoted about the axis of the hinge 23 through approximately 180° toits folded position by movement downwardly and then upwardly andforwardly. During this movement of the assembly the inclined axis of thehinge 23 has the effect that the assembly also progressively moves toone side of the vertical longitudinal plane of the bicycle so that bythe time it has reached its folded position, i.e. travelled throughapproximately 180°, it lies generally in a plane inclined relative tothe vertical longitudinal plane. The relative inclination of the twoplanes is sufficient for the rear wheel 20 to move far enough to theside of the frame 10 to be able to overlap the main member 11 thereof inside elevation of the bicycle. By contrast to prior art arrangements, inwhich the rear wheel in the folded state lies below the frame, theability of the wheel 20 to overlie a significant part of the frame, thusthe main member 11 and also part of the down tube 12, results in aparticularly close relationship of the frame and folded assembly.

FIG. 1 shows the rear wheel assembly 19 in its use position, FIG. 2 theassembly in a position halfway between the use position and the foldedposition and FIG. 3 the assembly in its folded position. The last figureclearly demonstrates the compact format achievable through overlap ofthe main member 11 by the rear wheel 20.

Return of the rear wheel assembly 19 to the use position is achieved bymovement of the assembly in the reverse direction and recoupling of theupper stay 22 to the seat tube 13 by way of the quick-action fasteningand unfastening device 24. Both folding and unfolding of the rear partof the bicycle are thus accomplished quickly and easily.

When the front wheel carrier 18 is correspondingly folded to reduce thesize of the front part of the bicycle, the hinge connection of thecarrier to the steering assembly 18 allows the front wheel 17 to besimilarly brought into a position in which it overlaps the main member11 of the frame 10, but disposed on the other side of the frame from thewheel 20 of the folded rear wheel assembly 19. In this state, the twowheels can lie in substantially parallel planes, both at an angle to thevertical longitudinal plane of the bicycle. In order to maintain thisstate, the lower stay 21 of the rear wheel assembly 19 includes asemi-cylindrical coupling socket 25 co-operable with the afore-mentionedquick-release clamping mechanism of the front wheel to lock that wheelin position. The two assemblies are thereby locked together and thebicycle can be lifted and transported in folded state without risk ofunfolding. The coupling socket 25, for example, receives a spindle ofthe mechanism, and associated clamping components of the mechanism bearagainst end faces of the socket to keep the spindle in place.

The rear wheel 20 of the bicycle is driven by a conventionalsprocket-and-chain drive system comprising a drive sprocket 26 rotatedby pedals (not shown) rotatably mounted in the region of the junction ofthe down tube 12 and seat tube 13, a driven sprocket 27 coupled to androtatable with the hub of the rear wheel 20 and a chain 28interconnecting the sprockets. In practice, either or each of thesprockets will have the form of a plurality of sprocket wheels ofdifferent diameter selectably engagable by the chain to vary the drivetransmission ratio of the system, transfer of the chain from sprocketwheel to sprocket wheel being effected by a conventional derailleurmechanism 29. Movement of the rear wheel assembly 19 from the useposition (FIG. 1) to the folded position (FIG. 3) produces slack in thechain 28 liable to cause it to disengage from one or other of thesprockets 26 and 27. To counteract this, the bicycle includes a chaincollecting device specifically to take up chain slack. The devicecomprises a bracket 31 provided with an upper cylindrical deflectingbobbin 32 and a lower cylindrical deflecting bobbin 33 disposed in frontof and slightly below the upper bobbin. The disposition of the bobbinsis such that on movement of the rear wheel assembly downwardly towardsits folded position the circumferential surface of the upper bobbin 32engages the underside of the top run 28 a of the chain 28 and thecircumferential surface of the lower bobbin 33 engages the underside ofthe lower run 28 b of the chain. With continuing movement of theassembly to the folded position the upper bobbin 32 produces aprogressively increasing bend in the upper run 28 a in direction awayfrom the lower run 28 b and the lower bobbin 33 correspondingly producesa progressively increasing bend in the lower run 28 b in directiontowards the upper run 28 a, the two bends taking up slack in the chainas it occurs. An early stage of formation of the bends in the two runsis apparent in FIG. 2. As the rear wheel assembly 19 approaches thefolded position the chain runs 28 a and 28 b cross over one another, asshown in FIG. 3. The two runs are also constrained to extend obliquelythrough the vertical longitudinal plane of the bicycle as a consequenceof location of the drive sprocket 26 and bobbins 32 and 33 on one sideof the plane and the rear wheel 20—in the folded state of the rear wheelassembly—on the other side of that plane. The two bobbins have flangesat their free ends remote from the bracket 31 to prevent the chain runsfrom slipping off the bobbins.

Deflection of the chain runs 28 a and 28 b by the bobbins 32 and 33 toremove slack from the chain is assisted by the derailleur mechanism 29,which is spring-loaded to constantly induce tension in the chain.

A final feature to reduce the area of the rear part of the bicycleconsists of provision of a seat post 34 which is slidably engaged in theseat tube 13 and, in the use state of the bicycle, protrudes from theupper end of the tube. The post 34 carries a seat 35 and is retained inthe use setting, illustrated in FIG. 1, by a quick-release clamp 36. Thepost 34 is retractible into the tube 13 and, in particular, to such anextent that a lower end portion of the post emerges from the tube 13 viaan open lower end thereof. The seat 35 can thus be brought into aposition close to the main member 11 of the frame 10. Return of the seatto the use position is by simple extension of the post 34 from the tube13 and reapplication of the clamp 36.

The area of the front part of the bicycle can be similarly reduced byfolding the handlebars 16 to partly overlie the frame 10.

A bicycle embodying the invention thus allows attainment of particularlyfavourable minimum dimensions of the rear part of the bicycle when inthe folded state of the rear wheel assembly, but without compromisingthe rigidity of the assembly in the use position.

1-21. (canceled)
 22. A folding bicycle including a frame with a mainmember extending in the fore and aft direction of the bicycle and havinga forward end and a rearward end with respect to said direction, a rearwheel assembly comprising a rear wheel, the assembly being disposed inthe region of said rearward end of the main member of the frame andbeing pivotably connected with the frame to be movable between a useposition in which the rear wheel of the assembly in side elevation ofthe bicycle is disposed rearwardly of the frame and a folded position inwhich the rear wheel in the side elevation is in part disposed alongsidethe main member, chain drive means including a chain for driving therear wheel, and a chain collecting device disposed to be clear of thechain during driving of the rear wheel and engageable with the chain soas to take up slack therein on movement of the rear wheel assembly fromsaid use position to said folded position.
 23. A bicycle according toclaim 22, wherein the collecting device comprises deflecting means toengage an upper and a lower run of the chain during movement of theassembly from the use position to the folded position and toprogressively deflect the runs by formation in the upper run of a benddirected away from the lower run and by formation in the lower run of abend directed towards the upper run.
 24. A bicycle according to claim23, wherein the deflecting means is engageable with an underside of eachchain run.
 25. A bicycle according to claim 23, wherein the deflectingmeans is arranged to cause the deflected chain runs to cross over oneanother during movement of the assembly from the use position to thefolded position.
 26. A bicycle according to claim 23, wherein thedeflecting means comprises curved guide surfaces for deflection of thechain runs therearound.
 27. A bicycle according to claim 26, wherein thecurved guide surfaces comprise parts of circumferential surfaces ofcylindrical elements.
 28. A bicycle according to claim 27, wherein theelements are mounted on a bracket attached to the base of the frame. 29.A bicycle according to claim 22, wherein the assembly is pivotablyconnected with the frame to be pivotable about an axis disposed at suchan inclination relative to the centre vertical longitudinal plane of thebicycle when the bicycle is upright that in said use position the rearwheel lies in or substantially in the longitudinal plane and in saidfolded position in a plane inclined relative to the longitudinal plane.30. A bicycle according to claim 29, wherein the inclination isapproximately 5°.
 31. A bicycle according to claim 22, wherein theassembly is pivotable through approximately 180° between said useposition and said folded position.
 32. A bicycle according to claim 22,wherein the assembly is pivotably connected with the frame in a rearwardbase region thereof.
 33. A bicycle according to claim 22, wherein theassembly is additionally detachably connected with the frame at aspacing from the pivotable connection of the assembly with the frame.34. A bicycle according to claim 22, comprising a steering assemblydisposed in the region of a forward end of the frame and carrying afront wheel movable between a use position in which the wheel in sideelevation is disposed forwardly of the frame and a folded position inwhich the wheel in the side elevation is disposed partly alongside themain member at a side of the frame remote from the rear wheel in thefolded position of the rear wheel assembly.
 35. A bicycle according toclaim 34, wherein the front and rear wheels are disposed insubstantially parallel planes in the folded positions of the front andrear wheel assemblies.
 36. A bicycle according to claim 34, wherein therear wheel assembly comprises coupling means able to be coupled with thefront wheel to lock it in the folded position.
 37. A bicycle accordingto claim 22, wherein the frame comprises a seat tube receiving a seatpost which protrudes from an upper end thereof and carries a seat, theseat post being retractable and extensible relative to the seat tube andthe seat tube being open at a lower end thereof to permit the seat postto extend out of the tube at the lower end when retracted.